无误差

The computational results show that the assumptions of incompressible water and massless foundation can considerably simplify the complexity of equations and cut the amount of computation, but cause little errors.

计算结果分析表明：在高拱坝流固耦合动力分析中，水体不可压缩和无质量地基假定可显著地消减方程复杂度和计算工作量，但带来的数值误差较小。

The non-reference-signal's adaptive digital filter algorithm of multi-sensor data fusion in the course of adaptive filter can be done without reference signals. It can adjust convergence constant automatically, it can also be recurred with real gradient value. Thus the field to apply the adaptive filter is widened, the convergence speed of the adaptive filter is sped up, the weighted disadjustmend is decreased, so that the last error of mean square approaches its minimum value more.

这章研究的基于多传感器数据融合无参考信号的自适应数字滤波算法其在自适应滤波过程中具有不用参考信号与自动调整收敛因子及使用实际梯度值进行递推的特点，这样不仅可扩大自适应滤波的使用范围，而且还使自适应滤波的收敛速度加快有效地减小权失调，从而使最后的均方误差更接近于其最小值。

In data space, multi-stage anti-aliasing digital filters are designed on the basis of the Nyquist sampling theorem and the minimax criterion to ensure that the observational data are sampled and stored without distortion.

在数存空间内，依据奈奎斯特定理和最大误差最小化的原则，设计多级抗混叠数字滤波器，使实测数据经过滤波器后，达到无失真抽样与存储的目的。

In this paper, an improved sensorless control strategy, which is based on the detection of zero crosspoints of back-EMF, is proposed. In this method, only one feed back signal is needed to sense terminal voltages and no motor neutral line is required. The phase shifter errors in traditional methods are eliminated.

本文同时提出了一种改进的无位置传感器检测方法，这种方法基于反电势过零点检测的基本原理，采用单路位置反馈信号，无须引出电机中性线，硬件结构简单，消除了传统检测方法中由于深度滤波产生的相移和误差。

The step motor can receive digital signal directly and has the ability to response outer environment immediately and has no accumulation error, which often is used in driving system. In this driving system, open-loop control system is composed of stepping motor, which can satisfy the demand not only for control precision but also for the target of economic and practicality. On this basis , the analysis of stepping motor in power calculating and style selecting is also given.

由于步进电机能够直接接收数字量，响应速度快而且工作可靠并无累积误差，常用作数字控制系统驱动机构的动力元件，因此，在驱动装置中采用由步进电机构成的开环控制方式，这种方式既能满足控制精度的要求，又能达到经济性、实用化目的，在此基础上，对步进电机的功率计一算及选型问题经行了分析。

This approach utilizes the fact that if the centerline of target image gets through the center point of the image plane,perspective projection and parallel projection must have the same image-forming property.

依据在目标成像的中轴线通过像面中心的时候，平行投影法和透视投影法有相同的成像特征这一事实，提出了一种无模型误差的修正平行投影法。

Many single BP networks make up of predictive model paratactically, each predictive model can not be affected each other, so the error is not accumulate.

由多个单独 BP 网以并行方式构成预测模型，各子预测模型间无直接影响，因此没有误差积累。

The frequency spectrum of the electric field, produced by an electric current dipole on the surface of the uniform conductive and polarizable earth, is transformed into time spectrum, with or without some random error added, and the time spectrum is then inversely transformed into the frequency domain.

基于层状导电和可极化大地表面，电偶源电场的时间谱在无随机干扰和有随机干扰时，进行频谱转换的计算结果，证明了时—频转换的误差传递问题严重。

We give the approximation formulas of the variance of the sample ratio estimator for a population mean and its asymptotically non-biased estimator in multi-stage sampling.

讨论多阶段抽样比率估计及其样本量选择的问题，给出了比率估计抽样均方误差的近似公式及其渐近无偏估计的公式。

Kinematics model of the suspension be reduced to truss structure, but as each bar is absolutely rigid, hinge point is also considered to be only a pure rotation without any deformation of rubber parts, such results have a certain margin of error.

运动学模型中把悬架简化成杆系结构，而各个杆件看成是绝对刚性的，铰点处也认为是只有纯转动而无任何橡胶件的变形，这样所得的结果就有一定的误差。

I can still vividly recall the impressive scenes you gave. You were among my friends and relatives who accompanied me from my house to the seaport and when the porters were slow to show up, you obligingly carried my suitcase for me.

你对我的种种感人情意，使我记忆犹新，那天你随着我的亲友从家里送我上轮船，搬运工迟迟不来，你毅然替我提着皮箱上船。

St. Nicholas became the patron saint of Russia, where he was famous for his red cape, flowing white beard, and bishop's mitre.

圣尼古拉成了俄罗斯人的守护神，在那里，他以身披红斗篷，留着飘逸的白胡须，戴着主教法冠而闻名。